Remove skin and debone chicken. Shred chicken into small threads, placing the cleaned chicken in a medium bowl. Melt butter in a small sauté pan and sauté the celery and onions until translucent. Meanwhile, in a separate medium mixing bowl, mix blue cheese, cream cheese, sour cream and shredded Cheddar with a spatula. Mix sautéed celery and onions into the cheese mixture. Toss shredded chicken with the Buffalo sauce, then add to cheese mixture and mix well. Refrigerate until ready to serve. Serve hot or cold.